Method of manufacturing heat-radiating units



March 1929. H. s. DODSON ETAL 6 6 METHOD OF MANUFACTURING HEAT RADIATINC' UNITS Filed June 2 1927 i g i T 5 g umentoz \Z6'o/a Jc0// poa. 5% J/WyJi/iarg Patented Man '19, 1929.

UNITED STATES HAROLD SCOTT DODSON, OF ROYAL OAK AND STEPHEN J.

, MICHIGAN.

MARX, F DETROIT,

METHOD or MANUFACTURING HEAT-RADIATIfiG UNITS.

Application filed June 2,

This invention relates to a heat radiating unit and more particularly to a tubular member provided with radiating fins, and to the method of constructing the same. a A number of tubes are usually assembled to form a radiator through which steam or hot water is circulated for heating purposes or for the. purpose of dissipating the heat of the circulating fluid, and it is found that the efiiciency of such a device is greatly enhanced by increasing the radiating surface by means of applying spaced thin metal fins to the tubes, and that the efi'iciency of such a device is further increased by so as sembling the fins and tubes that each fin will be and remain in firm contact throughout its inner periphery with the tube.

The practice heretofore has been to string annular thin sheet metal fin members upon a tube and then provide an intimate connection between fin and tube by soldering or otherwise attaching the fin to the tube. Such methods do not provide a connection which will be maintained under all conditions in use and the thickness of metal is increased,

thus decreasing the efficiency of the unit.

The present invention contemplates the assembly of fins on a tube in such a manner as to obviate the necessity for separate means for attaching the fins to the tube and so as to insure theimaintaining under all conditions of use, a firm contact between time and edge of fin, by stresses set up in the fin and which stresses will act under varying conditions of expansion and contraction to maintain an intimate contact. between the tube andfin, such stresses being secured through the angular relation of the fin to the tube'surface and the method of assembly.

diameter of the tube vto which they are to be applied, assembling these fin members uponthe tube in spaced relation with said fins free to tilt laterally or assume a dished condition and at the same time limiting such dishing or lateral inclination whereby ,a heat radiating The invention further contemplates the se- 1927. Serial No. 195,978.

stresses are set up in said fin members, which stresses cause each fin member to tend toward assuming its original flat condition or to contract upon the tube, thus firmly gripping the tube and forcing the inner edge of each fin into intimate contact with the tube surface. The invention further consists in' providmg a unit for the purpose, comprising a tubeand normally flat but laterally flexed annular thin sheet metal. fin members held with their inner edges in firm contact with the tube surface by the tendency of said fins to assume their normal flat condition, and in providing a tube with dished fins whereby air passing transversely of said tube is deflected by said fins into contact. with said tube surface.

The invention also consists in the matters hereinafter set forth and more particularly pointed out in the appended claims, reference being had to the accompanying drawmg in which Figure 1 is a side elevation, with certain fin members in section, of a portion of a unit illustrative of an embodiment of the present invention;

Fig. 2 is a detail of a portion of the unit showing a fin member partially in section; Fig. 3 is a transverse sectional detail;

F ig; 4 is a detail showing a fin blank inclevation and in section; and

Fig. 5 is a sectional view of a fin holder illustrative of means for use in practicing the method forming a part of the present invention.

It will be understood that a radiator, or device is made up of any desired number of units, a portion of one of which is shown prising a tube 1 and a series of spaced apart fin members 2 each formed from an annular thin sheet metal blank 3 shownin Fig. 4. These blanks are stamped from a sheet of thin metaland are of annular form and substantially flat with their internal diameter slightly less than the external diameter of the tube 1 to which they are to be applied.

In practicing the present method of constructing the unit, any suitable means may be employed for assembling the fins on the tube and limiting the lateral inclination of each fin, as well as properly spacing the fins apart, but as illustrative of practical means in Fig. 1, each unit com I creases outwardly from the inner edge there-- for the purpose, a fin holder 4 is illustrated in sectionin Fig. 5, which 'holder, as indicated by the line 5, is made in halves so that the two parts or halves of the holder may be separated after the fins have been assembled on the tube therein, in order that the assembled unit may be removed therefrom. The holder-is formed with a series of spaced interior grooves 5 opening into the bore of the holder, which grooves are preferably of substantially i-sh'ape in cross-section or at least have one wall which is inclined to a plane at right angles to the axis of the bore, which bore is of slightly. greater diameter than the external diameter of the tube 1 so that said tube may be passed longitudinally into the bore. The blanks 3 are of an external diameter substantially equal to the diameter of the bottom of the grooves so that these fin blanks may be set in the several grooves with their outer edges fitting within the bottoms of the grooves and held thereby. With the fin blanks in place in the holder, the tube 1 is forced longitudinal- 17 into the bore of the holder and through the fin blanks, the internal diameter of which blanks is slightly less than the external diameter of the tube. In thus fore ing the tube through the fins,'the fin blanks are dished by being forced laterally by the contact of the end of the tube with their inner peripheries as the tube is forced through, the inclined wall 6 of each groove limiting the lateral dishing of the fins and the expansion or stretchingof the fin blanks being limited by the. contact of their external peripheries with the bottoms of the grooves. The dishing of each.

fin by forcing its inner portion laterjally, sets up a tension in the metal which deof and also curves the fin transversely to a slight degree so that its natural tendency is to contract or spring back to its original fiat condition and this tension causes the finto grip the tube and holdiits inner edge in firm contact with the tube surface, maintaining such contact throughout the varying degrees of expansion and contraction due to temperature changes in use.

It is important that the degree of inclination or dishing of the fins be just sufiicient to permit thetube to be forced through the fins without rupturing the sheet metal or unduly stretching the same, and not so great as to impart to the fin a tendency toward further dishing. ,The dishing of the fin permits the insertion of the tube therethrough without fracturing the metal of the fin and without imparting a set to the metal which would destroy its tendency to spring back to its normal fiat condition, and by limiting each fin against expansion along its periphery and toe Eertain definite lateral angle or dish, a tension is set up in the inner the blank or blanks.

woe-rose portion of each fin which causes it to tightly embrace the tube and maintain its inner edge in firm contact with the tube surface.

The lateral inclination of each fin from a plane at right angles to the tube axis, provides a deflecting surface against which air passing between the fins impinges and is deflected toward and around the tube so that a greater proportion of tube surface is contacted by the air-and a greater cooling effect is secured thereby.

Ubviously, the slight curve which is given each fin when itis dished by forcing the tube therethrough, not only enlarges the opening in the fin sufficiently to permit the fin to pass, but also puts a'spring tension in the fin which causes the inner edge of the fin to closely engage the tube during all conditions of use, and by properly proportioning the opening in the fin blank to the external diameter of the tube, and properly limitin the angle of inclination or dishing of the fin, it becomes unnecessary to provide othermeans than-this tension, to hold the fin firmly in place and in perfect contact with the tube. I

Obviously, any suitable means may be employedto limit the inclination of the fins and the method contemplates the stringing of the fin blanks on the tube, one or more at a time, or the forcing of the tube through Other changes'in the construction and method described, are contemplated and the appended claims should be construed to include all such changes or modifications as fall within the terms thereof.

What we claim is 1. The method of constructing units eaclr each having an opening of less diameter than the external diameter of the tube and dishing the blank by forcing said tube through said opening, to cause said blank, by its natural tendency to assume its normal fiat condition, to contract upon the tube.

2. The method of assembling fins and tubes which comprises providing fin blanks each having an opening of less diameter than the external diameter of the tube upon which they are to be assembled and then assembling the blanks upon the tube and restraining the fins to a definite lateral 1n- 'clination during such assembly.

3. The method of assembling fins and.

tubes which consists in forcing a tube through a, fin blank having an opening of lesser diameter than the external diaineter of the tube and simultaneously confining the blank peripherally and to a, definite lateral angle less than a right angle to the tube axis.

4. The method of constructing heat radiating units each comprising a tube and fins on the tube, which method comprises provicling normally fiat sheet metal blanks; each having an opening of less diameter than the external diameter of the tube upon which they are to be assembled, and then dishing the blanks by forcing the tube endwise through the openings in the blanks and simultaneously restraining said blanks limit the dishing thereof and to retain the natural tendency of the blanks to assume their flat condition.

In testimony whereof we affix our sin-nutures.

HAROLD SCOTT DODSOX. STEPHEN J. MARX. 

